There are many applications where a metal is dissolved in a solution during an industrial process and it is desired either for reclaimation or other purposes to separate the metal from the solution. Examples of such applications include the electrowinning of metals from solutions in which such metals have become deposited during various industrial processes and the redepositing of metal from the electrolyte of a battery during the charging of the battery.
A problem in the deposition of metals from a solution in an electrochemical cell is that the dendritic or mossy growth of the metal layer results in a porous and uneven deposit which can span the interelectrode gap and short circuit the cell if the cell is either run for any substantial period of time or after a relatively short number of charge-discharge cycles of a storage battery. Good results in overcoming this problem and in achieving dense and homogeneous deposits have been acheived by utilizing various techniques to increase the relative movement between the negative electrodes and the electrolyte and/or to increase the mass of metal from the electrolyte solution in the immediate area of the negative electrode. These objectives have been obtained in for example U.S. Pat. No. 3,783,110 (issued Jan. 1, 1974 to I. Ahmad and entitled "Process for Electrodeposition of Metals Under the Influence of a Centrifugal Force Field") by creating a very high centrifugal force which is directed towards and substantially perpendicular to the metal-collecting face of the negative electrode. U.S Pat. No. 3,591,466 (issued July 6, 1971 to S. Heiman and entitled "Composite Structure Production") utilizes a similar technique to produce composite materials and U.S. Pat. No. 4,521,497 (issued June 4, 1985 to P. Tamminen and entitled "Electrochemical Generators and Method for the Operation Thereof") utilizes a high centrifugal force applied to the metal-collecting face of the negative electrode during charging of an electrochemical generator to retard dendrite growth. While the techniques indicated above are suitable if all that is required is a homogeneous and dense metal deposit, they are not readily adapted to the continuous electrowinning of metal from a solution.